Connect all the separate polygon objects into a single object and export only that.  When you export from Cinema/Riptide, make sure you're using the Riptide Group tag to handle polygon groups.  You don't have to do anything really special for material selections, just make sure that each material zone has a material defined in Cinema and assigned to each material selection, but if you want the "parts" (I assume you mean groups that are to be rigged in Poser's Setup room) then you need to apply a Group tag and set the polygon selections that are to be handled as Poser groups.

Import the OBJ file in Poser with all options un-checked.

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